Variable speed wind turbines with pitch control means are well known in the art.
These control means include at least an actuator and an adjusting transmission connected to a control device.
The control device receives input data from selected wind turbine components and sends output data to the actuator for changing the angular position of the blades according to certain rules allowing the implementation of operational methods intended for optimisation of the power production and for protection of the wind turbine in the event of high wind speeds or wind turbine failures.
One of these events is an extreme operating wind gust which produces extreme loads on main structural components such as the blade root and the tower bottom. In this case, the known art usually proposes using said control means for shutting down the turbine. For example, WO 2004/077068 describes the use of lidar means for detecting gusts long before the wind change reaches the turbine tower so that the blades could be feathered using the pitch control means.
The objective of this invention is a method to deal with this case keeping the wind turbine in operation and minimizing the bending moments in the blade root and in the tower bottom.